以所有可能的组合拆分数组(非常规拆分) [英] Split an array in all possible combinations (not regular splitting)

问题描述

在投反对票之前，请仔细阅读此问题.在这里的其他问题中找不到我的问题.

Please read this question carefully before down voting. I could not find my problem in other questions here.

假设我有一个数组，

>>> import numpy as np
>>> array  = np.linspace(1,4,4, dtype=np.int)
>>> array
array([1, 2, 3, 4])

我想要一个函数，可以将该数组拆分为所有可能的部分，例如，

I want a function that will split this array in all possible parts, such that,

不拆分:

([1,2,3,4])

分为2个部分:

([1], [2,3,4])
([1,2], [3,4])
([1,2,3] ,[4])

分为3个部分:

([1], [2], [3,4])
([1,2]), [3], [4])
([1], [2,3], [4])

分为len(array)个部分:

([1],[2],[3],[4])

我知道有np.split(array, r)，但是不会给出所有可能的分割.例如np.split(array, 2)会给出

I know there is np.split(array, r), but it will not give all possible splits. e.g. np.split(array, 2) will give,

[array([0, 1]), array([2, 3])]

如您所见，这不是我所需要的.如何满足我的需求?

As you can see this is not what I need. How to achieve my need?

推荐答案

您可以使用 来生成索引，该索引将在循环内根据拆分次数进行拆分:

You could use itertools.combinations to generate the indices where to split inside a loop over the number of splits:

>>> from itertools import combinations
>>> [np.split(array, idx) 
...  for n_splits in range(5) 
...  for idx in combinations(range(1, len(array)), n_splits)]
[[array([1, 2, 3, 4])],
 [array([1]), array([2, 3, 4])],
 [array([1, 2]), array([3, 4])],
 [array([1, 2, 3]), array([4])],
 [array([1]), array([2]), array([3, 4])],
 [array([1]), array([2, 3]), array([4])],
 [array([1, 2]), array([3]), array([4])],
 [array([1]), array([2]), array([3]), array([4])]]

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